Japan distributes Xocova, first domestic COVID drug

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First domestic COVID drug

Medical institutions in Japan have started prescribing the first domestically-developed COVID-19 drug, Xocova, following emergency approval by the health ministry in late November.

The ministry says the oral medication, developed by pharmaceutical company Shionogi & Co., has been confirmed to be safe and is estimated to be effective for people aged 12 and older. It says Xocova can be used even by low-risk patients to alleviate mild cases of COVID. Tests show the drug can shorten symptoms by about 24 hours. A course of treatment involves taking one pill a day for five days, and patients should start within three days of the onset of symptoms.

Until now, Japanese hospitals and clinics have been relying on imported COVID drugs that are only recommended for people at risk of serious illness, partly due to a dearth of clinical testing on low-risk patients, but also because of limited stocks.

While a steady supply of Xocova will widen the treatment options, the new drug comes with some restrictions of its own. Health authorities say it is not safe for pregnant women. They also caution that Xocova should not be taken in conjunction with certain other medications.

Potential game changer for medical system

Morishima Tsuneo, a visiting professor at Aichi Medical University, says the significance of the pill lies in the fact it can be prescribed to people who ostensibly fall into a low-risk category, because even these patients could end up developing serious symptoms.

He notes that while the pandemic fatality rate is declining with the Omicron variant, COVID continues to aggravate pre-existing chronic diseases and cause death at a much higher rate than the flu. He also points out that Japan has had fewer coronavirus infections per capita than many countries, meaning immunity across the board is lower, therefore the need for treatments greater.

Young patients eager for relief

A clinic in Saitama Prefecture, north of Tokyo, is already prescribing Xocova to COVID patients. Fujikawa Makiko, a doctor at the clinic, says staff have received inquiries from younger and less vulnerable patients who want a drug to treat sore throats and coughs. She says it's too early to comment on the efficacy of the pill, but that at the very least it doesn't appear to cause serious side effects.

Distribution of Xocova

The health ministry has signed a contract with Shionogi to buy enough Xocova to treat 1 million people. To start with, it has provided stocks to nearly 3,000 hospitals and clinics across the country, initially to those with experience prescribing Paxlovid, an oral medicine by Pfizer that works in a similar way to Xocova. It plans to expand supply to more locations in the weeks ahead.

Clinical trials

Shionogi ran clinical trials in Japan and two other countries from February to mid-July. It tested the drug on 1,821 people ranging in age from 12 up to their 60s. The test subjects had mild to moderate symptoms, and included patients thought to be at minimal risk of serious illness, and people who had been vaccinated.

In late September, the company announced that the results showed the drug was effective at alleviating symptoms and shortening their duration.

Symptoms resolve 24 hours sooner

The tests assessed the impact of Xocova on five symptoms – cough, sore throat, runny nose/nasal congestion, fatigue, and fever. A group of patients who started taking the drug within three days of the onset of their symptoms and continued taking one pill a day for five days found their symptoms resolved after around seven days, 24 hours sooner than people who took a placebo. The first group's viral load had dropped by around 97 percent after four days of treatment.

Shionogi says it didn't observe any critical side effects, and that the trial showed the drug was effective against variants, including the dominant BA.5 Omicron subvariant.

Warning for pregnant women and people taking certain drugs

The company says that in trials on animals, Xocova was shown to impact the fetus of pregnant test subjects. Consequently, it advises against prescribing the pill to pregnant women and women who may be pregnant. The firm also warns that people taking other medicines, such as for chronic illnesses, may experience side effects when combining those drugs with Xocova, so they should also avoid taking it.

Next step: full authorization

Shionogi received emergency approval to sell the drug under a system that Japan introduced this year to expedite the release of medications that are presumed to be effective but haven't yet undergone final clinical testing. The company now has to furnish the health ministry with additional data on the efficacy and safety of the pill, and apply for regular authorization within a year.

This process, which usually takes a year, is a strict and cumbersome one that experts blame for the delay in Japan's approval for vaccines. The emergency system was envisaged as a way around the red tape. But even under this new, streamlined process, Shionogi encountered delays.

Ono Shunsuke, an expert on pharmaceutical jurisprudence and an associate professor at the University of Tokyo, says no one seems to be clear on what hurdles an experimental drug needs to clear to win emergency authorization.

He says the ministry needs to make the process more transparent, and set specific thresholds for applicants to meet.

This information is accurate as of December 8, 2022.